The present invention relates to a lens case for storing, cleaning and/or sterilizing a pair of contact lenses, and more particularly to a lens case which provides for mounting of the contact lenses in side-by-side relation, and is designed to facilitate removal of the lenses as well as to insure against overheating of the lenses during sterilization.
Until recently only contact lenses of a relatively hard nature were available, and while these required cleaning, sterilization was not a significant problem. There has now been developed a soft contact lens manufactured from a hydrophilic plastic material; i.e., a relatively porous plastic material that will absorb water, and upon doing so becomes soft and pliable. While hard lenses must be cleaned and sterilized periodically, the need for sterilization with respect to soft lenses is more acute, due to the relatively porous nature of the plastic nature which provides a medium for bacteria. As such soft contact lenses must be effectively cleansed or sterilized on a regular basis, preferably daily.
Two sterilization methods have been developed and approved for use with soft lenses. The first and most popular involves the disposition of the lenses in a saline solution, and the heating of the saline solution to a temperature sufficient to destroy any bacteria that might be present. The other method, employs the use of a chemical process to destroy the bacteria and thereby achieve sterilization. With regard to heat sterilization, this is accomplished either by a "wet heat" type sterilizing process, or a more recently developed "dry heat" process. With respect to the former, the lenses are placed in a case which includes the saline solution, and then the case is placed in a second vessel of water which is brought to the boiling point, the heat being transferred to the sterilizing case by way of the surrounding water. With the "dry heat" method of sterilization, the lenses are disposed within a case and the saline solution added, and the case is placed in direct contact with the heater, such that there is direct application of heat to the surface of the container and from there to the sterilizing solution.
The use of hard and soft lenses has resulted in the development of a number of prior art type lens cases, examples of which are shown in U.S. Pat. Nos. 3,770,113; 3,977,517; and 4,009,777. These prior designs, however, while suitable for wet heat sterilization, are not well adapted for use with the dry heat type of sterilization. As will become clear from the discussion to follow, the lens case of the present invention was designed with the problems attendent with dry heat sterilization in mind, and to avoid these problems. While the lens case of the present invention was developed primarily for use with dry heat sterilization, the design includes a number of structural and operational features which are advantageous regardless of whether the case is used to store hard lenses, or is used in a wet heat type of sterilization process. More specifically, the lens case of the present invention is designed to accommodate the lenses in a horizontally disposed side-by-side relation in a relatively shallow casing structure. The casing structure is horizontally elongate, thereby providing a large surface area for engagement with a heating element. Further, the lens case is designed for inverted positioning of the lenses with respect to the heater unit. More specifically, the lenses are carried by a supporting arrangement affixed to the base of the case, such that when the base and cover are engaged to close the case, the lenses are spaced from the wall section of the cover. In use, the case is inverted so that the planar surface of the cover is in direct engagement with the heating element rather than the base. This feature has a specific advantage, in that the path for direct heat conduction through the case from the heater to the lens is lengthened appreciably. Accordingly, the most direct path for heat transfer to the lenses is via the sterilizer solution which is what is desired. Accordingly, with this arrangement it is assured that the sterilizing solution will be heated to a desired temperature before any overheating of the lenses can occur. Without the inverted mounting, the planar wall surface of the base would be in direct contact with the heater unit. It can be appreciated that with this arrangement a direct path of heat transfer exists from the heater to the lenses via the base structure, and as such portions of the lenses which engage the structure may be overheated, resulting in the possibility of damage to the lenses.
Another problem which is obviated to a great degree by the present invention is the removal of the lenses from the lens case. With the prior art type cases such as illustrated in U.S. Pat. Nos. 3,977,517 and 3,770,113, there is employed a stationary, convex support surface for the lenses and a pivotally mounted cover which overlies said support surface. After sterilization and upon opening of the covers, it is not uncommon for the lenses to adhere to the cover. When this occurs, the user may experience difficulty in locating the lens, and when located, it thus becomes necessary that the user contact or engage the inner or concave lens surface with his or her finger, in order to remove the lenses from the cover. This contact can often lead to contamination of the inner lens surface which is that surface engaged against the eye. Thus, the act of removal of the lens from the sterilizing case can negate that which was accomplished by the sterilizing procedure.
With the present invention, as will be discussed in detail hereinafter, there is provided a structure which enables a user to disengage the lenses from the cover structure, and insure that they will remain disposed upon the convex support surface upon opening of the cover structure. The user then need only contact the outer or convex lens surface in placing the lens on the eye, avoiding all contact and possible contamination with the inner lens surface. As an additional matter, it will be appreciated that the lens are relatively clear, and are not always easy to locate for removal from the case. This fact coupled with the prior art designs which employ oppositely mounted support structures, have contributed to the loss of numerous lenses. With the present invention, the lenses are mounted in side-by-side relation, with the lens covers opening in the same direction. This side-by-side mounting coupled with the structure to prevent adherence of the lenses to the cover greatly facilitate removal of the lenses, without the danger of loss or contamination thereof.